This is a scientific age. The communication between people in different continents has been made very convenient. This greatly expands the activity space of human beings. Thus, the entire globe is sometimes called a "village". Further, it is also desired that people can precisely identify the location of a person or an object whether moving or not. Thus a variety of Global Positioning System (GPS) and Global System for Mobile Communications (GSM) based communication equipment have been developed to fulfil such needs. Moreover, the use of such GPS and GSM based communication equipment have become a part of our daily life.
Conventionally, antenna of mobile phone and antenna of GPS based communication equipment are separated. That is, antenna of mobile phone can only receive communication signals, while GPS based communication equipment can only receive coordinate signals. As such, it is required to mount an antenna of mobile phone 11 and an antenna of GPS 12 on a digital communication equipment 10 for receiving GPS and GSM signals simultaneously as shown in FIG. 1. This inevitably increases cost as well as complicates installation procedure and wiring. It is thus much desired by the art to develop an antenna which can receive both communication signals from GSM and coordinate signals from GPS simultaneously.
Conventionally, a patch antenna is employed in GPS. Patch antenna has the advantages of compact, not susceptible to temperature change, and low power loss. As such, it is often that a patch antenna is mounted on a cylindrical member. One of such patch antennas is a ceramic patch antenna 20 as shown in FIG. 2. This ceramic patch antenna 20 is widely employed in GPS based communication equipment. As shown, patch antenna 20 comprises a substrate 21 made of ceramic material, a square or rectangular microstrip patch 22 and a ground plane 13 formed on the top and bottom respectively both by photolithography and etching, a coaxial cable 24 having a top feeding pin 241 penetrated through ground plane 23 and substrate 21 to contact with feeding point 221 of the microstrip patch 22, and an outer conductor 242 with part thereof being in contact with ground plane 23. This is a complete patch antenna 20. Further, signals are transmitted through feeding pin 241.
For receiving signals from GPS and GSM simultaneously, a typical implementation is to integrate patch antenna 20 of GPS and helical antenna 31 of GSM on sides of circuit board 30 as shown in FIG. 3. As such, it is possible to receive coordinate signals from GPS through patch antenna 20 and communication signals from GSM through helical antenna 31 respectively. As such, received signals are then filtered and amplified by electronics on the circuit board 30. Finally, signals are sent to digital communication equipment through cables 24 and 32 respectively. Such integration is advantageous over the one shown in FIG. 1. But it is still unsatisfactory for the purpose for which the invention is concerned for the following reasons:
1. Bulky. PA1 2. Complicated manufacturing processes. PA1 3. High cost.
Thus, it is desirable to provide an improved antenna for receiving signals from GPS and GSM having the advantages of slim, reliable, and inexpensive in order to overcome the above drawbacks of prior art.